What Your Tax Preparer Needs From Your Books, and By When

Updated 2026-10

The dates

Calendar-year S corporations and partnerships file by March 15 and can extend to September 15. Sole proprietors, single-member LLCs and C corporations file by April 15 and can extend to October 15. States set their own dates, some of them different, and your preparer confirms which apply. Estimated tax payments for the year ahead run quarterly from April.

An extension extends the filing, not the payment. Tax owed is due on the original date whatever happens, and that single fact decides most of what follows.

The package, for any entity

• Profit and loss for the year, reconciled to the bank, with the prior year alongside
• Balance sheet at year-end, reconciled: bank, cards, loans, deposits, sales tax, equity
• Fixed-asset list: anything bought that lasts more than a year, with date and cost
• Loan statements showing year-end balance and interest paid
• Payroll year-end reports and copies of filings, or the provider’s summaries
• 1099 data for anyone paid above the threshold, which is $2,000 for payments from 2026
• Sales tax collected and remitted, by state
• A list of anything unusual: a vehicle bought, a loan taken, an owner contribution, a lawsuit, a grant

What changes by entity

Sole proprietor or single-member LLC

Schedule C wants income and expenses by its own categories, home office detail, and mileage. A balance sheet is helpful but not filed.

S corporation

The return wants the balance sheet, officer compensation run through payroll, distributions, and figures the preparer uses to track each shareholder’s basis. This is the entity where un-reconciled books cause the most trouble.

Partnership

Like an S corporation, plus how profit, guaranteed payments and capital were allocated between partners, which the preparer takes from the agreement and the books.

C corporation

Balance sheet, retained earnings and any dividends; less common for the businesses that find this site, but the package is the same.

If the books are not ready

Tell the preparer early, before the deadline week. Ask whether they want an extension filed and what estimate they need to file it with. Then get the current year reconciled first, oldest months first, and hand it over as it completes rather than at the end. The preparer can work from a finished year while the rest is still being rebuilt. What to avoid is a return filed from a guess that will need amending; the extension guide explains why.

Making next year a formality

Books reconciled every month produce this package in a day in January. That is the quiet argument for monthly bookkeeping after a cleanup: the year-end stops being a project and the return gets filed on the original date.

Where to go next

• Behind on bookkeeping before a tax deadline
• Filing an extension with real numbers behind it
• Monthly bookkeeping after the cleanup